The overall goal of this research is to quantify multiple parkinsonian tremors in the orofacial motor system and examine the relationship between these various tremor forms and associated aberrations of voluntary speech movements. These objectives will be achieved through a series of hypothesis-directed experiments on Parkinson subjects using instrumental transduction of: 1) resting, postural, and action tremors in the lips, tongue, and jaw; 2) voluntary movement aberrations of these systems which have been implicated in explanations of parkinsonian dysarthria; and 3) fine force control in these orofacial systems. Analyses will focus on potential causal relationships between these tremors and the performance deficits. Parallel observations will be conducted in the limbs to enhance interpretations and provide critical perspectives on potential underlying nervous system processes. Potential clinical significance of instrumental tremor and movement measures will also be evaluated. These investigations will contribute to an understanding of the pathological and normal neural substrates of tremor and movement control, the functional relationship between system oscillations and the voluntary speech movement aberrations in Parkinson's disease, and the diagnosis and treatment of parkinsonian dysarthria. Twelve parkinsonian adults with a prominent tremor component and twelve adults free of neurological impairment will serve as subjects for each of the six proposed experiments. Parkinsonian tremors and associated performance deficits will be examined in the lips, tongue, jaw, and index finger using measures of structural movement, isometric force, electromyography, and acoustic signals. The specific experimental protocols will be varied to enhance the tremor and movement patterns to be measured. Time motion analyses will be accomplished via special measurement/data summary algorithms available on a PDP-11/44 computer. Frequency domain signal analyses will be implemented using a Hewlett-Packard (3582-A) real time spectrum analyzer communicating directly with the computer via a IB(V)-11A instrumentation bus controller.